Thousands of savers who used comparison website Confused.com to select a savings account have been misled, costing them up to £500 a year in lost interest, according to a recent investigation.

Channel Four's Dispatches said that the comparison website advertised poor-value savings accounts as "best buys" despite rates being up to 37pc lower than the actual best rates on the market.

The best Isa on Confused paid just 1.25pc, from NatWest, even though the top account paid 1.9pc, at Al Rayan Bank. Confused advertised just seven tax-free savings accounts, Dispatches found - whereas competitor website Moneysupermarket advertised 127.

This would cost a saver £101 over the course of a year, if they saved the maximum Isa allowance of £15,240.

For a three-year fixed bond, the best rate at Confused was just 2.16, from Vanquis Bank, far lower than the top rate on the market (2.5pc from Raphael Bank).

Dispatches compared four major comparison websites, Confused.com, Go Compare, Moneysupermarket and Comparethemarket, as part of the investigation. Confused.com's rivals offered far more choices.

A £10,000 bond would earn £35 less interest over the course of a year, if the saver took the poorer deal from Confused.com, it was claimed.

Savers who took these inferior "best buys" could lose up to £500 a year in lost interest, according to the programme.

This figure comprises interest that savers would forgo if they put £1,000 into an easy-access account, £10,000 into an Isa, £8,000 into a 3-year bond and £7,000 into a notice account according to Confused.com's recommendations, compared with the best deals for each product.